A key to accomplishing remote control and distributed execution is the data-sharing ability inherent to the Web. With new software programs, live data sharing can be as easy as simply right-clicking the item and placing a checkmark in a checkbox, which saves time for users and allows them to take advantage of the Web economies of scale such as efficient data transfer from one computer to another and the ability to access data in real time. Applications must also afford users real-time access to acquired data to control or monitor a process or perform a test across a network.

Sharing data leads to convenience—users can be remote while control applications are running, and contact methods can extend to mobile phones or pagers. For example, certain software programs allow users to send e-mail alerts. Electronic notifications can be created that allow operators to receive alerts from the production area via mobile phones or pagers when certain process values exceed established limits; at that point, the operator can log on to control the application. Such updates generated automatically during the testing process free up operator time to be spent on more productive tasks. As an example, this technique would be useful for a small company running burn-in tests, which can take six to 10 hours. With the type of system described above, the engineer could go back to his or her desk and receive an alert if test results don't fall within set test parameters.

With distributed execution tasks, the network enables users to access various measurement nodes. It is possible to develop software that uses each computer to complete a portion of the application; a test could have several acquisition nodes, each sharing data with the main computer or cluster of computers that perform the analysis, generate reports, and send them to the Web.

XML and other Strategies

For data sharing, extensible markup language (XML, which enables definition, transmission, validation, and interpretation of data between applications and organizations), is quickly becoming a standard way to

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transfer data in a text-readable fashion that can easily be displayed on the Web. Because of the universal XML standard, one can generate a Web report featuring a defined data set and easily import it into other applications. Because the data is readily accessible, applications can download any XML document, parse the data, and perform custom analyses. Some software applications now include built-in functions for creating or reading XML documents.

Manufacturers have realized the enormous cost benefits of using common off-the-shelf, Internet-related hardware and software components to communicate process data. The same technology used for Internet applications can also be used to connect the enterprise. On the plant floor, data acquisition and automation systems serve as information-access points to the larger corporate IT systems. Data can be transported using existing, widely accepted protocols to guarantee not only interconnectivity but also interoperability. The workforce is already trained to fetch and use data supplied through a browser.

NI’s DataSocket provides another method of sharing data directly with other parts of an organization. DataSocket implementation requires no extra development time—it streams the data in a graph or other user interface item over the network. Because DataSocket also is implemented as an ActiveX control, a Java Bean, and a component of Measurement Studio for C/C++ and Visual Basic development, users can incorporate the technology in many other applications. Project members who want to subscribe to the DataSocket Server item that contains the data use a URL to begin receiving data and any updates sent. With DataSocket, engineers can generate Web pages to display quality    information from a manufacturing floor, changing properties of materials during an ongoing test, or even updates of the weather.

The Drawbacks

Although remotely controlling applications and distributing control via the Web has countless benefits related to operator convenience, as well as company time and cost savings, operators should also be cognizant of possible drawbacks. High amounts of traffic on the network could lead to slow updates or data transfer. The method of communication (Ethernet) is not a deterministic bus and offers no guarantee that data or execution will occur in a reliable amount of time.

Security is often a concern of Internet-related activities. If the remote system is on the same network as hundreds or millions of other users, the potential exists for possible system interference. Test and control applications should be implemented so that the network is protected by

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existing IT security systems. Best practices call for users to work with IT professionals to determine the best way to implement Web-based control applications without interfering with the particular IT system security.

In addition, many people could be trying to access the same application simultaneously. This requires companies to choose applications capable of handling multiple users accessing at the same time. If multiple access to an application is not possible, the users ultimately accomplish no more than they would through a single transaction.

The benefits of Web-based control far outweigh the disadvantages. Although certain hindrances may occur as a result of doing business on a network shared by millions, die advantages of convenience, cost, and time prompt software developers to investigate new ways to deal with the potential problems. For example, to avoid user confusion, software constraints can limit access so that only one client can control the application at a time, but that control can pass easily among the various clients at run-time. In addition, the host computer can take control of the application away from any of the remote clients at any time. The technique can also minimize cost by allowing service personnel to control and test remotely, for example.

The Internet is changing the way we control our applications by providing new ways to take measurements and distribute results. Many different options exist for remotely controlling applications and distributing execution. The best software programs allow users to take advantage of the power of the Web without having to become experts in any of its technologies, helping them incorporate the Internet into many different aspects of their application. This allows companies to integrate their applications easily into the existing corporate networking infrastructure so they can increase the productivity of those performing control.